JP7735896B2 - Photosensitive resin composition, wiring board, and method for manufacturing wiring board - Google Patents

Description

The present invention relates to a photosensitive resin composition, a wiring board, and a method for manufacturing a wiring board.

In recent years, touch panels have become widely used as an input method. A touch panel consists of a display unit such as an LCD panel and a touch panel sensor that detects information input at a specific position. Touch panel types can be broadly categorized into resistive, capacitive, optical, electromagnetic induction, and ultrasonic types depending on how they detect the input position. Of these, capacitive touch panels are widely used due to their optical brightness, excellent design, simple structure, and excellent functionality.

A capacitive touch panel sensor has a second electrode that is perpendicular to a first electrode via an insulating layer. A voltage is applied to the electrodes on the touch panel surface, and when a conductive object such as a finger touches the surface, the sensor detects a change in capacitance, outputting the contact position as a signal. Known examples of capacitive touch panel sensors include those with electrodes and external connection terminals formed on a pair of opposing transparent substrates, and those with electrodes and external connection terminals formed on both sides of a single transparent substrate.

Transparent wiring electrodes have typically been used in touch panel sensors to reduce their visibility. However, in recent years, due to the trend toward higher sensitivity and larger screens, opaque wiring electrodes made of metallic materials have become more common. Touch panel sensors with opaque wiring electrodes made of metallic materials have had the problem of the opaque wiring electrodes being visible due to their metallic luster. One method proposed for reducing the visibility of opaque wiring electrodes is to form an opaque wiring electrode on a transparent substrate, then apply a black positive-tone photosensitive composition to the substrate, and then expose and develop the positive-tone photosensitive composition using the opaque wiring electrode as a mask to form a light-shielding layer on the opaque wiring electrode (see, for example, Patent Document 1). One example of a black positive-tone photosensitive composition used in this method is a photosensitive resin composition containing a pigment, novolac resin, a carboxyl-containing acrylic resin, a photoacid generator, and an amine-based dispersant (see, for example, Patent Document 2).

International Publication No. 2018/168325 Japanese Patent Application Laid-Open No. 2021-139971

However, when a light-shielding layer was formed on an opaque wiring electrode using the photosensitive resin composition described in Patent Document 2, good results were obtained in terms of light-shielding properties and patterning properties. However, when a weather resistance test was conducted, it was found that the resistance value of the opaque wiring electrode tended to increase, and there was room for improvement in terms of weather resistance.

In view of the above-mentioned problems, the present invention aims to provide a photosensitive resin composition that can suppress an increase in the resistance value of an opaque wiring electrode even when used in combination with the opaque wiring electrode.

In order to solve the above problems, the present invention provides a photosensitive resin composition comprising (a) a pigment, (b) a novolak resin, (c) a quinone diazide compound, and (d) a compound represented by the following general formula (1), wherein the content of the (d) compound is 3 to 10 mass % of the solid content.

(In the above general formula (1), X ¹ to X ⁴ each independently represent a hydrogen atom, a carboxyl group, a hydroxyl group, a nitro group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms.)

According to the present invention, a photosensitive resin composition can be obtained that can suppress an increase in the resistance value of an opaque wiring electrode even when used in combination with the opaque wiring electrode.

1 is a schematic diagram illustrating an example of a wiring board according to the present invention. FIG. 1 is a schematic diagram showing electrode patterns for evaluating visibility and conductivity in Examples and Comparative Examples.

[Photosensitive resin composition]
The photosensitive resin composition of the present invention comprises (a) a pigment, (b) a novolac resin, (c) a quinone diazide compound, and (d) a compound represented by the general formula (1), and the content of the compound (d) is 3 to 10 mass % of the solid content. Here, "photosensitive" means that when the photosensitive paste is irradiated with actinic rays, the chemical structure of the photosensitive organic component changes through reactions such as photocrosslinking, photopolymerization, photodepolymerization, and photomodification. The photosensitive resin composition of the present invention must be a positive-type photosensitive resin composition whose chemical structure changes upon irradiation with actinic rays, making it soluble in a developer. Here, actinic rays refer to light in the wavelength range of 250 to 1100 nm that causes such chemical reactions. Specific light sources include ultraviolet light from ultra-high-pressure mercury lamps, metal halide lamps, LED lamps, etc.; visible light from halogen lamps, etc.; and laser beams of specific wavelengths from helium-cadmium lasers, helium-neon lasers, argon ion lasers, semiconductor lasers, YAG lasers, and carbon dioxide lasers. In the photosensitive resin composition of the present invention, ultraviolet light having a wavelength in the range of 300 to 500 nm can be preferably used.

A light-shielding layer formed using the photosensitive resin composition of the present invention can be formed, for example, on top of an opaque wiring electrode in a touch sensor panel, making the opaque wiring electrode less visible.

[(a) Pigment]
The photosensitive resin composition of the present invention contains (a) a pigment. By containing (a) the pigment, the formed light-shielding layer has light-shielding properties.

(a) Pigments include organic pigments and inorganic pigments, and two or more of these pigments may be contained. The proportion of (a) pigment is preferably 5 to 30% by mass of the solid content.

Examples of organic pigments include soluble azo pigments, insoluble azo pigments, metal complex azo pigments, phthalocyanine pigments, and condensed polycyclic pigments.

Examples of inorganic pigments include carbon black, graphite, pine soot, ultramarine, iron oxides such as iron black, hematite, goethite, and magnetite, titanium, chromium, lead, and composites of these metals.

[(b) Novolac Resin]
The photosensitive resin composition of the present invention contains (b) a novolac resin. By containing (b) a novolac resin, developability is improved. Here, "developability" refers to the resistance of unexposed areas to dissolution in a developer, and the better the developability, the less the pattern line width is scraped off even when immersed in a developer for a long period of time.

(b) Novolac resin is obtained by polycondensing phenols and aldehydes using a known method. Two or more types of novolac resins may be contained. The proportion of (b) novolac resin contained is preferably 50 to 80 mass% of the solid content.

Examples of the phenols include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, and 3,4,5-trimethylphenol. Two or more of these phenols may be used.

Examples of the aldehydes include formalin, paraformaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, and chloroacetaldehyde. Two or more of these aldehydes may be used.

[(c) Quinone diazide compound]
The photosensitive resin composition of the present invention contains (c) a quinone diazide compound. By containing the (c) quinone diazide compound, it is possible to impart positive photosensitivity, which increases the solubility of the actinic ray-irradiated area in an alkaline developer. The proportion of the (c) quinone diazide compound is preferably 5 to 25 mass % of the solid content.

(c) Examples of quinone diazide compounds include those in which the sulfonic acid of quinone diazide is bonded to a polyhydroxy compound via an ester bond, those in which the sulfonic acid of quinone diazide is bonded to a polyamino compound via a sulfonamide bond, and those in which the sulfonic acid of quinone diazide is bonded to a polyhydroxy polyamino compound via an ester bond and/or a sulfonamide bond.

[(d) Compound represented by general formula (1)]
The photosensitive resin composition of the present invention contains (d) a compound represented by the following general formula (1) (sometimes simply referred to as "compound (d)" in this specification). By containing compound (d), metal ions eluted from the opaque wiring electrode by ultraviolet light or visible light are captured, and a complex film is formed on the surface of the opaque wiring electrode, thereby suppressing the elution of additional metal ions and suppressing an increase in the resistance value of the opaque wiring electrode.

In the above general formula (1), X ¹ to X ⁴ each independently represent a hydrogen atom, a carboxyl group, a hydroxyl group, a nitro group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

In particular, it is preferable that at least one of X ¹ to X ⁴ is a carboxyl group. By having at least one of X ¹ to X ⁴ be a carboxyl group, volatilization in the curing step described below can be suppressed, and an increase in the resistance value of the opaque wiring electrode can be further suppressed even at high temperatures exceeding 200°C.

Preferably, at least one of X ¹ to X ⁴ is a methyl group. By having at least one of X ¹ to X ⁴ be a methyl group, volatilization during the curing step is suppressed, and an increase in the resistance value of the opaque wiring electrode can be further suppressed even at high temperatures exceeding 130°C.

Examples of hydrocarbon groups include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Aliphatic hydrocarbon groups may be straight-chain or branched, and may be partially or entirely cyclic. They may also be saturated or unsaturated hydrocarbon groups. In aliphatic hydrocarbon groups, at least some of the hydrogen atoms may be substituted with halogens or the like. In aromatic hydrocarbon groups, at least some of the hydrogen atoms may be substituted with halogens or the like. The hydrocarbon group has 1 to 20 carbon atoms, preferably 1 to 10.

X ¹ to X ⁴ may be the same as or different from each other.

The structure of general formula (1) can be confirmed by assigning the peaks detected using a nuclear magnetic resonance (NMR) spectrometer.

(d) Examples of compounds include 1,2,3-benzotriazole, carboxybenzotriazole, tolyltriazole, and nitrobenzotriazole.

The content of the (d) compound is 3 to 10 mass% of the solid content. If the content of the (d) compound is less than 3 mass% of the solid content, the effect of suppressing an increase in resistance value will be insufficient. The content of the (d) compound is preferably 4 mass% or more. On the other hand, if the content of the (d) compound is more than 10 mass% of the solid content, more metal in the opaque wiring electrode will be captured than necessary, resulting in an increase in resistance value. The content of the (d) compound is preferably 6 mass% or less.

The content of compound (d) in the solids can be measured as follows. First, to determine the solids ratio, the photosensitive resin composition is diluted with chloroform or the like, filtered, and the filtrate is subjected to GC/MS measurement to qualify the solvent component. Next, a standard solution of the solvent component is prepared using a standard of the appropriate solvent, adjusted to a desired concentration with chloroform or the like, and a calibration curve is created by GC measurement. Furthermore, the photosensitive resin composition is diluted with chloroform or the like, filtered, and the filtrate is subjected to GC measurement. The concentration of the solvent component is calculated using the created calibration curve. The obtained solvent component concentration is subtracted from 100% to determine the solids ratio. Similarly, to determine the concentration of compound (d), the photosensitive resin composition is diluted with acetonitrile or the like, filtered, and the filtrate is subjected to LC/MS measurement to qualify the compound (d). Next, a standard solution of the appropriate standard is prepared using acetonitrile or the like, adjusted to a desired concentration, and a calibration curve is created by LC/UV or LC/MS measurement. The photosensitive resin composition is then diluted with acetonitrile or the like, and the filtrate is filtered and subjected to LC/UV or LC/MS measurement. The concentration of compound (d) is calculated using the calibration curve created. The content of compound (d) in the solids can be calculated using the ratio of these solids and the concentration of compound (d).

In the photosensitive resin composition of the present invention, the molecular weight of the (d) compound is preferably 130 to 240. When the (d) compound has a molecular weight of 130 or more, volatilization during the curing process when forming the light-shielding layer (described below) is suppressed, and an increase in the resistance value of the opaque wiring electrode can be further suppressed. On the other hand, when the (d) compound has a molecular weight of 240 or less, the necessary amount can be minimized. The molecular weight of the (d) compound can be calculated from the atomic weight after identifying the structure using NMR.

[(e) Methylol-based compounds]
The photosensitive resin composition of the present invention preferably further contains (e) a methylol-based compound. By containing the (e) methylol-based compound, crosslinking of the (b) novolac resin is promoted by heat, and an increase in the resistance value of the opaque wiring electrode can be further suppressed. The content of the (e) methylol-based compound is preferably 1 to 15 mass % of the solid content, and more preferably 3 to 7 mass %.

Commercially available methylol compounds can be used, including Nikalac MW-390, Nikalac MW-100LM, Nikalac MX-750LM, Nikalac MX-270, and Nikalac MX-280 (all manufactured by Sanwa Chemical Co., Ltd.).

[solvent]
The photosensitive resin composition of the present invention may contain a solvent, such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethyl sulfoxide, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, γ-butyrolactone, ethyl lactate, 3-methoxy-3-methylbutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, propylene glycol monomethyl ether acetate (hereinafter referred to as "PGMEA"), dipropylene glycol monomethyl ether, ethylene glycol monobutyl ether, and butyl carbitol acetate.

[Other ingredients]
The photosensitive resin composition of the present invention may contain additives such as polymers, plasticizers, surfactants, silane coupling agents, crosslinking agents, leveling agents, antifoaming agents, or pigments, as long as the desired properties of the composition are not impaired.

[Wiring board]
The wiring board of the present invention has an opaque wiring electrode on a transparent substrate and a light-shielding layer on the opaque wiring electrode, and the light-shielding layer is a cured product of the above-mentioned photosensitive resin composition.

The transparent substrate is transparent in the visible light region. Here, "transparent" means that the transmittance at a wavelength of 550 nm is 80% or more. The transmittance of the transparent substrate at a wavelength of 550 nm can be measured using a UV-visible spectrophotometer (U-3310, manufactured by Hitachi High-Technologies Corporation).

Transparent substrates include inflexible and flexible transparent substrates. Inflexible transparent substrates include, for example, quartz glass, soda glass, chemically strengthened glass, Pyrex (registered trademark) glass, synthetic quartz plates, epoxy resin substrates, polyetherimide resin substrates, polyetherketone resin substrates, and polysulfone resin substrates. Flexible transparent substrates include, for example, transparent films and optical resin plates made of resins such as polyethylene terephthalate film (hereinafter referred to as "PET film"), cycloolefin polymer film, polyimide film, polyester film, and aramid film. Multiple of these may be used in layers; for example, multiple transparent substrates can be bonded together using an adhesive layer.

The opaque wiring electrode is patterned on at least one side of the transparent substrate. Here, "opaque" means that the transmittance at a wavelength of 550 nm is 25% or less.

Examples of materials that can be used to form the opaque wiring electrode include metals such as silver, gold, copper, platinum, lead, tin, nickel, aluminum, tungsten, molybdenum, chromium, titanium, and indium, as well as alloys of these metals. Of these, silver or copper is preferred from the perspective of conductivity. The opaque wiring electrode may also be formed by hardening a conductive composition containing conductive particles. In this case, the conductive particles are preferably spherical, and the aforementioned metals and alloys can be used as the material.

The opaque wiring electrode may be formed on one or both sides of the transparent substrate, or two or more layers may be formed on one side via a transparent protective layer, etc.

The light-shielding layer is formed on the opaque wiring electrode and is a cured product of the above-mentioned photosensitive resin composition.

In the wiring board of the present invention, the ratio of the thickness T1 of the transparent wiring electrode to the thickness T2 of the light-shielding layer is preferably T1:T2 = 1.0:1.5 to 2.0:1.0, and the sum of T1 and T2 is preferably 1.0 to 3.0 μm. By increasing the ratio of the thickness T1 of the transparent wiring electrode to T2 = 1.0:1.5 or more, electrical conductivity is improved. Furthermore, by increasing the ratio of the thickness T2 of the light-shielding layer to T1:T2 = 2.0:1.0 or more, visibility is improved. Furthermore, when the sum of T1 and T2 is 1.0 μm or more, both electrical conductivity and visibility can be improved. It is more preferable that the sum of T1 and T2 is 1.2 μm or more. Furthermore, by keeping the sum 3.0 μm or less, unevenness is reduced, making it easier to form a protective layer on the wiring board. The thicknesses of the transparent wiring electrode and the light-shielding layer can be measured by SEM observation of a cross section of the wiring board.

In the wiring board of the present invention, the difference in line width between the opaque wiring electrode and the light-shielding layer is preferably 1.0 μm or less. By keeping the difference in line width between the opaque wiring electrode and the light-shielding layer 1.0 μm or less, it is possible to minimize a decrease in the transmittance of the wiring board and a deterioration in visibility due to reflection from the opaque wiring electrode protruding from the light-shielding layer. It is more preferable that the difference in line width between the opaque wiring electrode and the light-shielding layer be 0.5 μm or less. The difference in line width can be measured using an optical microscope (Keyence Corporation VHX-6000) from the surface on which the opaque wiring electrode is formed if the opaque wiring electrode is thicker, or from the transparent substrate side if the opaque wiring electrode is thinner.

The wiring board of the present invention may have a transparent protective layer on the opaque wiring electrode and the light-shielding layer. Examples of methods for forming the transparent protective layer include applying a transparent resin composition and drying it, or laminating a transparent adhesive film to the surface on which the opaque wiring electrode is formed.

[Method for producing photosensitive resin composition]
Next, a method for producing the photosensitive resin composition of the present invention will be described.

After mixing (a) pigment, (b) novolac resin, (c) quinone diazide compound, and (d) compound, the dispersion can be prepared using a dispersing machine or kneader such as a jet mill, bead mill, ball mill, or planetary ball mill.

[Method of manufacturing a wiring board]
Next, a method for manufacturing a wiring board according to the present invention will be described.

The method for manufacturing a wiring board of the present invention preferably includes the steps of forming an opaque wiring electrode on a transparent substrate, applying the photosensitive resin composition to the surface on which the opaque wiring electrode is formed, and exposing the photosensitive resin composition from the side opposite the applied surface using the opaque wiring electrode as a mask, followed by development, to form a light-shielding layer on the opaque wiring electrode. This allows the formation of a light-shielding layer with the same pattern as the opaque wiring electrode.

First, an opaque wiring electrode is formed on a transparent substrate.

Methods for forming opaque wiring electrodes include, for example, photolithography using a photosensitive conductive composition to form a pattern; screen printing, gravure printing, inkjet printing, or other methods using a conductive composition (conductive paste) to form a pattern; and etching a film of metal, metal composite, metal-metal compound composite, or metal alloy, etc., using photolithography to form a pattern. Among these, photolithography using a photosensitive conductive composition is preferred because it allows for the formation of fine wiring. When forming opaque wiring electrodes on both sides of a transparent substrate, or when forming two or more layers of opaque wiring electrodes via a transparent protective layer, each opaque wiring electrode may be formed by the same method, or different methods may be combined.

The method for forming a pattern by photolithography using a photosensitive conductive composition involves a coating step in which the photosensitive conductive composition is applied to a transparent substrate to form a coating film, a photolithography step in which the coating film is exposed to light and developed to form a pattern, and a curing step in which the pattern is heated at 100 to 300°C to form a conductive pattern.

The coating process is a process in which the photosensitive conductive composition described above is applied to a transparent substrate to obtain a coating film. Methods for applying the photosensitive conductive composition to a transparent substrate include, for example, spin coating using a spinner, spray coating, roll coating, screen printing, or coating using a slit coater, blade coater, die coater, calendar coater, meniscus coater, or bar coater.

If the photosensitive conductive composition contains a solvent, a drying step may be included in which the resulting coating film is dried to remove the solvent. Methods for drying the coating film include, for example, heat drying in an oven, on a hot plate, or by infrared irradiation, or vacuum drying. The heat drying temperature is typically 50 to 120°C, and the heat drying time is typically one minute to several hours.

The photolithography process is a process in which the coating film obtained in the coating process is exposed to light and developed to obtain a pattern. The light source used to expose the coating film is preferably a mercury lamp or an LED lamp with i-line (365 nm), h-line (405 nm), or g-line (436 nm). A conductive pattern is obtained by exposing the coated surface of the photosensitive conductive composition on the transparent substrate through an exposure mask, and then removing the unexposed areas with a developer.

Examples of developers for alkaline development include aqueous solutions of tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate, and surfactants may be added to these aqueous solutions.

Examples of developers for organic development include polar solvents such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, or hexamethylphosphortriamide, or mixed solutions of these polar solvents with methanol, ethanol, isopropyl alcohol, xylene, water, methyl carbitol, or ethyl carbitol.

Development methods include, for example, spraying the developer onto the surface of the coating film while the substrate is stationary or rotating, immersing the substrate in the developer, or applying ultrasound while immersing the substrate in the developer.

The pattern obtained in the development step may be rinsed with a rinse solution. Examples of rinse solutions include water, or an aqueous solution of water to which an alcohol such as ethanol or isopropyl alcohol, or an ester such as ethyl lactate or propylene glycol monomethyl ether acetate, or a surfactant has been added.

The curing temperature in the curing process is preferably 100 to 300°C. Curing methods include, for example, heat drying using an oven, inert oven, or hot plate, heat drying using electromagnetic waves such as an infrared heater, or vacuum drying.

Next, the photosensitive resin composition of the present invention is applied to the surface on which the opaque wiring electrode is formed.

The coating and drying processes can be carried out in the same manner as for the opaque wiring electrode.

Next, the photosensitive resin composition is exposed to light from the side opposite the coated surface using the opaque wiring electrode as a mask, and then developed to form a light-shielding layer on the opaque wiring electrode. This results in a light-shielding layer pattern similar to that of the opaque wiring electrode, as shown in Figure 1.

More preferably, the method includes the steps of forming an opaque wiring electrode on a transparent substrate, applying the photosensitive resin composition to the surface on which the opaque wiring electrode is formed, exposing the photosensitive resin composition from the coated side using an exposure mask, exposing the photosensitive resin composition from the side opposite the coated side using the opaque wiring electrode as a mask, and developing the photosensitive resin composition exposed from both sides to form a light-shielding layer on the opaque wiring electrode. This makes it possible to remove the light-shielding layer from areas where it is necessary to ensure electrical continuity with external elements, such as terminal portions, and where it is desired to expose the opaque wiring electrode.

The curing process can be carried out in the same way as for the opaque wiring electrode.

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The materials used in each example and comparative example are as follows:

[(a) Pigment]
Carbon black (MA100 manufactured by Mitsubishi Chemical Corporation)
Titanium nitride particles (average primary particle size: 30 nm).

[(b) Novolac Resin]
Phenol novolak (WR-101 manufactured by DIC Corporation).

[(c) Quinone diazide compound]
TDF-517 (manufactured by Toyo Gosei Co., Ltd.).

[(d) Compound]
VERZONE Crystal #120 (manufactured by Daiwa Kasei Co., Ltd., hereinafter referred to as "BTA", where X ¹ to X ⁴ are all hydrogen)
VERZONE C-BTA (manufactured by Daiwa Kasei Co., Ltd., one of X ¹ to X ⁴ is a carboxyl group and the remaining three are hydrogen)
VERZONE TTA (manufactured by Daiwa Kasei Co., Ltd., one of X ¹ to X ⁴ is a methyl group and the remaining three are hydrogen)
VERZONE N-BTA (manufactured by Daiwa Kasei Co., Ltd., one of X ¹ to X ⁴ is a nitro group and the remaining three are hydrogen).

[Dispersant]
・BYK-LP21116 (manufactured by BYK)
- BYK-9077 (manufactured by BYK-Chemie).

[Leveling agent]
・BYK-331 (manufactured by BYK)
- BYK-350 (manufactured by BYK-Chemie).

[(e) Methylol-based compounds]
- Nikalac MW-390 (manufactured by Sanwa Chemical Co., Ltd.).

[Transparent substrate]
- Alkali-free glass "AN Wizus (registered trademark)" (manufactured by AGC Inc.) (a-1)
PET film "Lumirror (registered trademark)" T60 (manufactured by Toray Industries, Inc.) (a-2).

[solvent]
PGMEA (Kuraray Co., Ltd.)
-Butyl carbitol acetate.

[Register]
LC-140 (manufactured by Rohm and Haas Electronic Materials Co., Ltd.).

[Resist Stripper]
-JELK-101 (manufactured by Kanto Chemical Co., Ltd.).

(Production Example 1: Carboxyl Group-Containing Acrylic Copolymer (C-1))
A reaction vessel under a nitrogen atmosphere was charged with 150 g of diethylene glycol monoethyl ether acetate (hereinafter, "DMEA") and heated to 80°C using an oil bath. To this was added dropwise a mixture consisting of 20 g of ethyl acrylate (hereinafter, "EA"), 40 g of 2-ethylhexyl methacrylate (hereinafter, "2-EHMA"), 20 g of styrene (hereinafter, "St"), 15 g of acrylic acid (hereinafter, "AA"), 0.8 g of 2,2'-azobisisobutyronitrile, and 10 g of DMEA over 1 hour. After completion of the dropwise addition, the polymerization reaction was carried out for an additional 6 hours. Thereafter, 1 g of hydroquinone monomethyl ether was added to terminate the polymerization reaction. Subsequently, a mixture consisting of 5 g of glycidyl methacrylate (hereinafter, "GMA"), 1 g of triethylbenzylammonium chloride, and 10 g of DMEA was added dropwise over 0.5 hours. After completion of the dropwise addition, the addition reaction was carried out for an additional 2 hours. The resulting reaction solution was purified with methanol to remove unreacted impurities, and then vacuum dried for 24 hours to obtain a carboxyl group-containing acrylic copolymer (C-1) having a copolymerization ratio (by mass): EA/2-EHMA/St/GMA/AA=20/40/20/5/15.

(Production Example 2: Photosensitive conductive paste (D-1))
Into a 100 mL clean bottle were placed 3.0 g of the carboxyl group-containing acrylic copolymer (C-1) obtained in Production Example 1, 0.3 g of photopolymerization initiator N-1919 (manufactured by ADEKA Corporation), 1.2 g of the monomer "Light Acrylate (registered trademark)" BP-4EA (manufactured by Kyoeisha Chemical Co., Ltd.), 0.5 g of dispersant BYK-LP21116, 79.0 g of PGMEA, 0.7 g of MA100, and 15.3 g of silver fine particles having a surface carbon coating layer with an average thickness of 1 nm and a particle diameter of 40 nm (manufactured by Nisshin Engineering Inc.), and mixed using a rotation-revolution vacuum mixer "Awatori Rentaro ARE-310" (manufactured by Thinky Corporation) to obtain 100.0 g of photosensitive conductive paste (D-1).

(Production Example 3: Photosensitive conductive paste (D-2))
Into a 100 mL clean bottle were placed 17.5 g of the carboxyl group-containing acrylic copolymer (C-1) obtained in Production Example 1, 0.5 g of photopolymerization initiator N-1919 (manufactured by ADEK Corporation), 1.5 g of epoxy resin "ADEKA RESIN (registered trademark)" EP-4530 (epoxy equivalent 190, manufactured by ADEKA Corporation), 3.5 g of monomer "Light Acrylate (registered trademark)" BP-4EA (manufactured by Kyoeisha Chemical Co., Ltd.), and 19.0 g of DMEA, and these were mixed using "Awatori Rentaro (registered trademark)" ARE-310 (manufactured by THINKY Corporation) to obtain 42.0 g of a resin solution. The resulting 42 g of resin solution was mixed with 62.3 g of Ag particles having a volume particle diameter of 0.3 μm and kneaded using a three-roller EXAKT M50 (manufactured by EXAKT). Then, 7 g of DMEA was added and mixed to obtain 111 g of a photosensitive conductive paste (D-2).

(Production Example 4: Substrate with Opaque Wiring Electrode (E-1))
The photosensitive conductive paste (D-1) obtained in Production Example 2 was applied to a transparent substrate (a-1) by spin coating so that the film thickness after drying would be 0.6 μm, and then dried at 90°C for 8 minutes. Next, as shown in FIG. 2, an exposure mask having a mesh portion and a mask light-shielding portion with a mesh pitch of 70 μm and a mesh angle of 90° was used to expose the substrate to light at an exposure dose of 100 mJ/cm ² (equivalent to a wavelength of 365 nm) using an exposure device (PEM-6M; manufactured by Union Optical Co., Ltd.). The mask opening width was 4 μm. Thereafter, development was carried out using a 0.1% aqueous tetramethylammonium hydroxide solution as a developer for a time twice the time it took for the exposed portion to dissolve, followed by rinsing with ultrapure water for 30 seconds and heating in a box oven at 240°C for 60 minutes to obtain a substrate with an opaque wiring electrode. The opaque wiring electrode-forming surface of the obtained substrate with an opaque wiring electrode was cleaned using a vacuum plasma device at 10 W for 10 seconds. The line width of the resulting opaque wiring electrode was measured with an optical microscope and found to be 4 μm, and the film thickness was 0.3 μm.

(Production Example 5: Substrate with Opaque Wiring Electrode (E-2))
A substrate with an opaque wiring electrode was obtained in the same manner as in Production Example 4, except that the coating was performed so that the film thickness after drying would be 2.0 μm. The line width of the obtained opaque wiring electrode was measured with an optical microscope and found to be 4 μm. The film thickness was also 1.0 μm.

(Production Example 6: Substrate with Opaque Wiring Electrode (E-3))
A substrate with an opaque wiring electrode was obtained in the same manner as in Production Example 4, except that the coating was performed so that the film thickness after drying would be 1.0 μm. The line width of the obtained opaque wiring electrode was measured with an optical microscope and found to be 4 μm. The film thickness was also 0.5 μm.

(Production Example 7: Substrate with Opaque Wiring Electrode (E-4))
The photosensitive conductive paste (D-2) obtained in Production Example 3 was applied to a transparent substrate (a-2) by screen printing so that the film thickness after drying would be 1.6 μm, and then dried at 100°C for 10 minutes. Next, as shown in FIG. 2, an exposure mask having a mesh portion and a mask light-shielding portion with a mesh pitch of 70 μm and a mesh angle of 90 degrees was used to expose the substrate to light at an exposure dose of 100 mJ/cm ² (equivalent to a wavelength of 365 nm) using an exposure device (PEM-6M; manufactured by Union Optical Co., Ltd.). The mask opening width was 3 μm. Thereafter, immersion development was performed in a 0.2 mass% sodium carbonate aqueous solution for 30 seconds, followed by rinsing with ultrapure water for 30 seconds and then heating in a box oven at 140°C for 60 minutes to obtain a substrate with an opaque wiring electrode. The opaque wiring electrode-forming surface of the obtained substrate with an opaque wiring electrode was subjected to a cleaning treatment using a vacuum plasma device at 10 W for 10 seconds. The line width of the obtained opaque wiring electrode was measured using an optical microscope and found to be 4 μm. The film thickness was 1.6 μm.

(Production Example 8: Substrate with Opaque Wiring Electrode (E-5))
A copper film was formed on one surface of the transparent substrate (a-2) using a sputtering method to a thickness of 2.0 μm over the entire surface. Next, a resist was applied to the copper film by spin coating and dried at 100°C for 5 minutes. Next, as shown in FIG. 2, an exposure mask having a mesh portion and a mask light-shielding portion with a mesh pitch of 70 μm and a mesh angle of 90 degrees was used to perform exposure at an exposure dose of 45 mJ/cm ² (equivalent to a wavelength of 365 nm) using an exposure device (PEM-6M; manufactured by Union Optical Co., Ltd.). The mask opening width was 8 μm. Thereafter, immersion development was performed in a 2.38% tetramethylammonium hydroxide aqueous solution for 30 seconds, and further rinsed with ultrapure water for 30 seconds. Next, etching was performed in a ferric chloride aqueous solution for 3 minutes, and further rinsed with ultrapure water for 30 seconds. Next, immersion development was performed in a resist stripper for 4 minutes, and further rinsed with ultrapure water for 30 seconds to obtain a substrate with an opaque wiring electrode. The opaque wiring electrode-formed surface of the obtained substrate with opaque wiring electrodes was subjected to a cleaning treatment using a vacuum plasma device under conditions of 10 W and 10 seconds. The line width of the obtained opaque wiring electrodes was measured using an optical microscope and found to be 4 μm. The film thickness was also found to be 2.0 μm.

(Production Example 9: Photosensitive Insulating Paste (F-1))
Into a 100 mL clean bottle were placed 15.5 g of the acrylic copolymer (C-1), 5.2 g of Light Acrylate (registered trademark) HPP-A, 0.3 g of photopolymerization initiator N-1919, and 79.0 g of PGMEA, and these were mixed using a rotation-revolution vacuum mixer "Awatori Rentaro ARE-310" to obtain 100.0 g of a photosensitive insulating paste (F-1).

<Evaluation of the difference in line width between the opaque wiring electrode and the light-shielding layer>
The wiring substrates obtained in each of the examples and comparative examples were observed from the opaque wiring electrode forming surface and from the transparent substrate side using an optical microscope (VHX-6000 manufactured by Keyence Corporation), and the difference in line width between the opaque wiring electrode and the light-shielding layer was measured.

<Evaluation of Resistance Value of Opaque Wiring Electrodes>
For each of the opaque wiring electrode-equipped substrate without a light-shielding layer and the wiring substrate after the light-shielding layer formed thereon obtained in each Example and Comparative Example, simulated sunlight was irradiated for 500 hours using a weather resistance tester Q-Sun Xe-3 (manufactured by Q-Lab) under conditions of 0.3 W/m ² (340 nm), a chamber temperature of 55°C, and humidity of 30%, and the resistance between the terminals before and after irradiation was measured using a resistance measurement tester (2407A; manufactured by BK Precision). The distance between the terminals was 17 mm, the width was 15 mm, and the pad portion 6 was 2 mm long and 15 mm wide. The rate of change in the resistance of the wiring substrate relative to the opaque wiring electrode-equipped substrate was calculated, and the rate of change was evaluated as "A" if it was less than 10%, "B" if it was 10% or more but less than 15%, "C" if it was 15% or more but less than 20%, "D" if it was 20% or more but less than 25%, and "E" if it was 25% or more.

<Evaluation of initial conductivity>
For the wiring boards obtained in each example and comparative example, the resistance between terminals was measured using a resistance tester. The distance between terminals was 17 mm, the width was 15 mm, and the pad portion 6 was 2 mm long and 15 mm wide. Resistance values less than 12 Ω were evaluated as "A," 12 Ω or more but less than 20 Ω as "B," and 20 Ω or more as "C."

<Visibility evaluation>
For the wiring boards obtained in each example and comparative example, a black film was placed on the side opposite to the surface on which the opaque wiring electrode was formed, and then light was projected onto the wiring board using a projector. Ten people were then visually inspected from a distance of 30 cm to evaluate whether the mesh-like electrode portion was visible. If it was visible to eight or more people, it was rated as "E," if it was visible to five or more but less than eight people, it was rated as "D," if it was visible to three or more but less than five people, it was rated as "C," if it was visible to one or more but less than three people, it was rated as "B," and if it was invisible to ten people, it was rated as "A."

Example 1
<Preparation of Photosensitive Resin Composition>
In a 100 mL clean bottle, 3.42 g of WR-101, 0.58 g of TDF-517, 0.26 g of BTA, 0.02 g of BYK-331, and 44.71 g of PGMEA were placed and mixed using a centrifugal-revolution vacuum mixer "Awatori Rentaro ARE-310" (manufactured by Thinky Corporation) to obtain 49.0 g of a resin solution. 49.0 g of the resulting resin solution, 0.64 g of carbon black, and 0.38 g of BYK-LP21116 were mixed and kneaded using an Ultra Apex Mill (manufactured by Kotobuki Industries Co., Ltd.) equipped with a centrifugal separator filled with 70% by volume of 0.05 mmφ zirconia beads (manufactured by Toray Industries, Inc.), to obtain 50.0 g of a photosensitive resin composition.

<Formation of light-shielding layer>
The obtained photosensitive resin composition was applied by spin coating onto a substrate (E-1) with an opaque wiring electrode so that the film thickness after drying on the opaque wiring electrode was 1.5 μm, and dried at 100 ° C. for 5 minutes. Using the opaque wiring electrode as a mask, it was exposed from the side opposite the opaque wiring electrode formation surface at an exposure dose of 500 mJ / cm ² (wavelength 365 nm equivalent). Then, using an exposure mask that shielded areas other than those corresponding to the pad portions of the opaque wiring electrode, it was exposed from the coated side of the photosensitive resin composition at an exposure dose of 500 mJ / cm ² (wavelength 365 nm equivalent) using an exposure device. Then, immersion development was performed for 50 seconds in a 2.38% tetramethylammonium hydroxide aqueous solution as a developer, and a light-shielding layer was formed on the top of the opaque wiring electrode. Furthermore, it was heated for 60 minutes in a box oven at 240 ° C. to obtain a substrate with a light-shielding layer.

<Formation of Transparent Protective Layer>
The photosensitive insulating paste (F-1) obtained in Production Example 9 was applied by spin coating to the opaque wiring electrode and light-shielding layer-formed surface of the obtained substrate with a light-shielding layer so that the film thickness after drying would be 1.5 μm, and then dried for 5 minutes at 80° C. Furthermore, using an exposure mask that shielded only the areas corresponding to the pad portions of the opaque wiring electrode, an exposure device (PEM-6M; manufactured by Union Optical Co., Ltd.) was used to expose from the side where the photosensitive insulating paste was applied at an exposure dose of 100 mJ/cm ² (equivalent to a wavelength of 365 nm). Thereafter, development was carried out for 30 seconds using a 0.1% aqueous tetramethylammonium hydroxide solution as a developer, and further, rinsing was carried out for 30 seconds with ultrapure water, followed by heating for 60 minutes in a box oven at 240° C. to obtain a wiring substrate as shown in FIG.

(Examples 2 to 9, Comparative Examples 1 to 3)
A wiring board as shown in FIG. 1 was produced in the same manner as in Example 1, except that the amounts of (b) novolak resin, (d) compound, and (e) methylol-based compound added and the type of (d) compound in <Preparation of photosensitive resin composition>, the substrate with opaque wiring electrode used in <Formation of light-shielding layer>, and the thickness T2 of the light-shielding layer were changed as shown in Table 1.

Example 10
<Preparation of Photosensitive Resin Composition>
Into a 100 mL clean bottle were placed 12.73 g of WR-101, 3.15 g of TDF-517, 1.34 g of VERZONE C-BTA, 0.08 g of BYK-350, 1.34 g of Nikalac MW-390, and 21.94 g of butyl carbitol acetate, and mixed using a rotation-revolution vacuum mixer "Awatori Rentaro ARE-310" (manufactured by Thinky Corporation) to obtain 40.58 g of a resin solution. 40.58 g of the obtained resin solution, 7.24 g of titanium nitride particles, and 2.18 g of BYK-9077 were mixed together and kneaded using an Ultra Apex Mill (manufactured by Kotobuki Industries Co., Ltd.) equipped with a centrifugal separator filled with 70% by volume of 0.05 mmφ zirconia beads (manufactured by Toray Industries, Inc.), to obtain 50.0 g of a photosensitive resin composition.

<Formation of light-shielding layer>
The obtained photosensitive resin composition was applied by screen printing onto a substrate (E-4) with an opaque wiring electrode so that the film thickness after drying on the opaque wiring electrode was 0.8 μm, and dried at 100 ° C. for 10 minutes. Using the opaque wiring electrode as a mask, it was exposed from the side opposite the surface on which the opaque wiring electrode was formed at an exposure dose of 500 mJ / cm ² (equivalent to a wavelength of 365 nm). Then, using an exposure mask that shielded only the areas corresponding to the pad portions of the opaque wiring electrode, it was exposed from the coated side of the photosensitive resin composition at an exposure dose of 500 mJ / cm ² (equivalent to a wavelength of 365 nm) using an exposure device. Then, immersion development was performed for 50 seconds in a developer of 2.38% tetramethylammonium hydroxide aqueous solution, and a light-shielding layer was formed on the top of the opaque wiring electrode. Furthermore, it was heated in a box oven at 140 ° C. for 60 minutes to obtain a substrate with a light-shielding layer.

<Formation of Transparent Protective Layer>
In the same manner as in Example 1, a wiring board as shown in FIG.

Example 11
A wiring substrate as shown in FIG. 1 was prepared in the same manner as in Example 10, except that the substrate with opaque wiring electrodes and the thickness T2 of the light-shielding layer used in <Formation of Light-Shielding Layer> were changed as shown in Table 1.

The evaluation results are shown in Tables 1 and 2.

1: transparent substrate 2: opaque wiring electrode 3: light-shielding layer 4: transparent protective layer 5: wiring substrate 6: pad portion

Claims (11)

A photosensitive resin composition comprising (a) a pigment, (b) a novolak resin, (c) a quinone diazide compound, and (d) a compound represented by the following general formula (1), wherein the content of the compound (d) is 3 to 10 mass % based on the solid content:
(In the above general formula (1), X ¹ to X ⁴ each independently represent a hydrogen atom, a carboxyl group, a hydroxyl group, a nitro group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms.) 2. The photosensitive resin composition according to claim 1, wherein at least one of X ¹ to X ⁴ is a carboxyl group. 3. The photosensitive resin composition according to claim 1, wherein at least one of X ¹ to X ⁴ is a methyl group. The photosensitive resin composition according to any one of claims 1 to 3, wherein the molecular weight of the (d) compound is 130 to 240. The photosensitive resin composition according to any one of claims 1 to 4, further comprising (e) a methylol compound. A wiring board having an opaque wiring electrode on a transparent substrate and a light-shielding layer on the opaque wiring electrode, wherein the light-shielding layer is a cured product of the photosensitive resin composition described in any one of claims 1 to 5. The wiring board of claim 6, wherein the ratio of the thickness T1 of the opaque wiring electrode to the thickness T2 of the light-shielding layer is T1:T2 = 1.0:1.5 to 2.0:1.0, and the sum of T1 and T2 is 1.0 to 3.0 μm. The wiring board described in claim 6 or 7, wherein the difference in line width between the opaque wiring electrode and the light-shielding layer is 1.0 μm or less. The wiring board described in any one of claims 6 to 8, wherein the opaque wiring electrode contains silver or copper. forming an opaque wiring electrode on a transparent substrate;
a step of applying the photosensitive resin composition according to any one of claims 1 to 5 to the surface on which the opaque wiring electrode is formed;
and exposing the photosensitive resin composition from the side opposite to the coated surface using the opaque wiring electrode as a mask, and developing the composition to form a light-shielding layer on the opaque wiring electrode. forming an opaque wiring electrode on a transparent substrate;
a step of applying the photosensitive resin composition according to any one of claims 1 to 5 to the surface on which the opaque wiring electrode is formed;
exposing the photosensitive resin composition from the coated surface side of the photosensitive resin composition using an exposure mask;
a step of exposing the photosensitive resin composition to light from the side opposite to the coated surface using the opaque wiring electrode as a mask;
and developing the photosensitive resin composition that has been exposed from both sides to form a light-shielding layer on the opaque wiring electrodes.